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Radionuclide Dosimetric Data Sheets
Iodine-125
Summary data
General
Classification
Isotope: I-125
Atomic number (Z): 53
Mass number (A): 125
Neutron number (N): 72
Radioactive decay
Decay modes: Electron capture
Half-life: 59.4 [d]
Decay constant: 1.3506e-07 [1/s]
Daughters: Te-125 (100.0%)
Radioactive daughters: None
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.01923 [MeV]
Mean photon energy: 0.04283 [MeV]
Air kerma rate constant, Γ10: 9.856e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 9.856e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 3.081e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 0.000e+00
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
3.081e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 6.862e-15
[Gy·kg/Bq·s]
Dose point kernels (plot)
Dose point kernel source: Graves, et al. Medical Physics. 2019 Nov.; 46(11):5284-5293.
Note: Bins are spaced every 0.1 mm until a radius of 10 cm, and every 1 mm until a radius of 2 m.
Download tabulated dose point kernel file here: www.mirdsoft.org/products/MIRDspecs/I-125 DPK.csv
Summary spectra (plot)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/I-125 Summary Spectrum.csv
Tabulated data
Summary spectra (table)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Note: Radiations with yield < 0.01 are excluded from the table, but are available in the linked *.csv data.
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/I-125 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.36106e-05 |
2.497e+01 |
X-ray |
|
3.75695e-03 |
6.476e-02 |
X-ray |
|
4.02446e-03 |
3.757e-02 |
X-ray |
|
2.71868e-02 |
4.052e-01 |
X-ray |
|
2.74652e-02 |
7.544e-01 |
X-ray |
|
3.09378e-02 |
6.946e-02 |
X-ray |
|
3.09901e-02 |
1.347e-01 |
X-ray |
|
3.16740e-02 |
1.439e-02 |
X-ray |
|
3.16841e-02 |
2.828e-02 |
X-ray |
|
3.54922e-02 |
6.680e-02 |
Gamma |
|
2.29271e-05 |
1.220e+01 |
Auger electron |
|
2.49224e-05 |
4.085e+00 |
Auger electron |
|
1.20899e-04 |
1.410e+00 |
Auger electron |
|
2.99843e-04 |
2.760e-01 |
Auger electron |
|
4.49679e-04 |
3.125e+00 |
Auger electron |
|
5.41735e-04 |
1.205e-01 |
Auger electron |
|
3.08817e-03 |
1.226e+00 |
Auger electron |
|
3.68276e-03 |
3.475e-01 |
Auger electron |
|
3.68720e-03 |
8.080e-01 |
Conversion electron |
|
4.29994e-03 |
2.459e-02 |
Auger electron |
|
2.26653e-02 |
1.310e-01 |
Auger electron |
|
2.65056e-02 |
5.769e-02 |
Auger electron |
|
3.05780e-02 |
9.686e-02 |
Conversion electron |
|
3.46773e-02 |
2.204e-02 |
Conversion electron |
Useful Links
Isotope decay characteristics are periodically updated as better measurements can be made - changes that may not be reflected on this page. Please see useful links:
National Nuclear Data Center (NNDC): https://www.nndc.bnl.gov/nudat3/mird/
International Atomic Energy Agency (IAEA) Livechart: https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
Reference Links
ICRP Report 107: https://www.icrp.org/publication.asp?id=ICRP%20Publication%20107
Graves et al. Dose Point Kernels: https://doi.org/10.1002/mp.13789
MIRD Decay Schemes 2nd Edition: https://sites.snmmi.org/SNMMI-MAIN/iCore/Store/StoreLayouts/Item_Detail.aspx?iProductCode=0-932004-80-6
MIRDsoft MIRDspecs version 20250101 (www.mirdsoft.org)
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